/**

  * Back 2 Browser Bytecode Translator

  * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, version 2 of the License.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. Look for COPYING file in the top folder.

  * If not, see http://opensource.org/licenses/GPL-2.0.

  */

 package org.apidesign.bck2brwsr.launcher;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import java.util.Enumeration;

 import java.util.LinkedHashSet;

 import java.util.Set;

 import java.util.logging.Logger;

 import javax.script.Invocable;

 import javax.script.ScriptEngine;

 import javax.script.ScriptEngineManager;

 import javax.script.ScriptException;

 import org.apidesign.vm4brwsr.Bck2Brwsr;

 /**

  * Tests execution in Java's internal scripting engine.

  */

 final class JSLauncher extends Launcher {

     private static final Logger LOG = Logger.getLogger(JSLauncher.class.getName());

     private Set<ClassLoader> loaders = new LinkedHashSet<>();

     private final Res resources = new Res();

     private Invocable code;

     private StringBuilder codeSeq;

     private Object console;

     @Override MethodInvocation addMethod(Class<?> clazz, String method, String html) {

         loaders.add(clazz.getClassLoader());

         MethodInvocation mi = new MethodInvocation(clazz.getName(), method, html);

         try {

             mi.result(code.invokeMethod(

                 console,

                 "invoke__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2",

                 mi.className, mi.methodName).toString(), null);

         } catch (ScriptException | NoSuchMethodException ex) {

             mi.result(null, ex);

         }

         return mi;

     }

     public void addClassLoader(ClassLoader url) {

         this.loaders.add(url);

     }

     @Override

     public void initialize() throws IOException {

         try {

             initRhino();

         } catch (Exception ex) {

             if (ex instanceof IOException) {

                 throw (IOException)ex;

             }

             if (ex instanceof RuntimeException) {

                 throw (RuntimeException)ex;

             }

             throw new IOException(ex);

         }

     }

     private void initRhino() throws IOException, ScriptException, NoSuchMethodException {

         StringBuilder sb = new StringBuilder();

         Bck2Brwsr.generate(sb, new Res());

         ScriptEngineManager sem = new ScriptEngineManager();

         ScriptEngine mach = sem.getEngineByExtension("js");

         sb.append(

               "\nvar vm = new bck2brwsr(org.apidesign.bck2brwsr.launcher.Console.read);"

             + "\nfunction initVM() { return vm; };"

             + "\n");

         Object res = mach.eval(sb.toString());

         if (!(mach instanceof Invocable)) {

             throw new IOException("It is invocable object: " + res);

         }

         code = (Invocable) mach;

         codeSeq = sb;

         Object vm = code.invokeFunction("initVM");

         console = code.invokeMethod(vm, "loadClass", Console.class.getName());

     }

     @Override

     public void shutdown() throws IOException {

     }

     @Override

     public String toString() {

         return codeSeq.toString();

     }

     private class Res implements Bck2Brwsr.Resources {

         @Override

         public InputStream get(String resource) throws IOException {

             for (ClassLoader l : loaders) {

                 URL u = null;

                 Enumeration<URL> en = l.getResources(resource);

                 while (en.hasMoreElements()) {

                     u = en.nextElement();

                 }

                 if (u != null) {

                     return u.openStream();

                 }

             }

             throw new IOException("Can't find " + resource);

         }

     }

 }